Popularity of means of the visual control of protected premises and grounds For the last years has considerably increased. This way of protection is applied by owners of private houses to supervision over territory adjoining to a structure. For this purpose videocameras become stronger over an entrance door, over an entrance place on a site, on the walls leaving on a backyard or economic constructions.
If signals of gauges can give the bare information on events on protected object videocameras give a full picture of an event. Connection of the chamber with a recorder gives the chance to learn about all objects appearing in protected territory for a long interval of time.
For normal functioning of system of video observation it is necessary to establish the videocameras connected among themselves, monitors for perception of the transferred information and technical devices for its processing. The personal computer which facilitates adjustment of equipment and management of its work can become one of links of this system.
For reception of the most exact picture of the events occurring in protected territory, it is desirable to have as much monitors, how many videocameras it is established on a site. If it is less than monitors, than chambers the greatest possible number of images simultaneously joins, and remained alternately replace each other on one of screens.
The computer Connected to security system gives the chance to receive on one screen of the image at once from 16 chambers. Thus a fragment demanding more careful studying, it is easily possible to increase till the sizes of the screen. However it is necessary to remember that the computer system of video observation spends for processing of the received information of more time, than usual television in which the image from each chamber arrives on the separate screen.
For supervision over the territory adjoining to the house, it is quite enough to use black-and-white chambers. Two chambers established definitely give a corner of the review to 180 °. For maintenance bolshego a review corner it is necessary to establish one chamber supplied with the rotary device.
Such device can turn the chamber on 1-12 ° in a minute. Therefore if the chamber is set up on supervision over an event in radius of 10 m in the field of vision those objects which speed of moving does not exceed 2 km/s will get only. For supervision over fast-moving subjects special adjustment of all entering into system of supervision of devices should be spent. .
Degree of protection of protected territory raises, if the video observation system includes extras. One of them react to infringement in a controllable zone inclusion of its full image on screens. Others put in action executing devices which include sound signals, bright light or locking mechanisms.
For such help in system it is possible to use movement and presence gauges. They can react definitely to the information received from chambers, including a recorder. At occurrence in protected territory of moving objects works an alarm signal.
Sensitivity of modern detectors can be changed by means of adjustment. If necessary it is possible to make so that the alarm signal did not move at movement on controllable territory of small objects - birds and animals. .
If it is required to provide the latent supervision over small space it is the most convenient to use compact and inexpensive beskorpusnye videocameras. They have the small motionless objective attached to a printing electronic payment which is mounted in a wall.
The Corner of the review of the chamber is directly connected with a focal length of an objective used in it. This dependence is presented to tab. 4.
Table 4. Dependence of a point of view of an objective on a focal length
| the Focal length, mm
|| the Point of view, a hailstones
The Chambers used for external supervision, often place in protective cases. At their application in places with a frigid climate the case is usually supplied with a heater. .
Chambers are very convenient For protection of the big territories, to operate with which it is possible distantsionno. By means of the computer program or the special panel it is possible to turn a chamber objective on a corner to 90 ° on a vertical and 175 ° across.
The Important part of system of external supervision are special devices for record of the image received from chambers. They are usually supplied by date and time generators and can work during long time. By means of the video printer it is possible to make the photographic image of any shot from a film. .
The special timer which allows the tape recorder to increase or reduce speed of record can be built in a recorder. Usually speed of record changes after reception from alarm signal gauges.
At installation of systems of supervision in the private house for connection of its parts in a single whole it is quite enough to use a usual television cable. .
To avoid discrepancy each other different parts of mounted system of video observation, it is necessary to entrust its choice and installation to professionals. At observance of service regulations of used technics it is capable to function normally long time.
Video on-door speakerphones
The Simplified variant of system of video observation is the video on-door speakerphone. It is established about an entrance door and, except the chamber and the monitor, incorporates a call and an intercom similar to phone. The videocamera joins by pressing a call, and at tube removal on the monitor there is an image of the person facing to a door. The small chamber can be built in an eye or to disguise in another way. In this case the come will not guess supervision conducted behind it.
It is expedient to establish also about an entrance door the button of the so-called disturbing alarm system, by pressing on which the alarm signal will arrive directly in police station.